ECE支TCP基因重复和功能分化对矮牵牛分枝和花型的影响

The flower industry thrives on novelty. Transcription factor (TF) gene duplication and diversification play important role in the evolution of morphological novelty of plant. So increasing knowledge of the relationship between TF gene duplication and diversification and ornamental traits variation should benefit to flower industry. TCP proteins are plant specific TFs which regulate cell proliferation and growth. ECE clade of TCP genes play critical roles in controlling shoot branching and flower symmetry. Petunia possesses slightly zygomorphic flowers and rich shoot branching variations, and can be genetically modified easily. It should be a good material for studying the function of the ECE clade of TCP genes, and also for creating novel flower. We plan to clone all the members of ECE clade genes in petunia and investigate them by qRT-PCR, insitu RNA hybridization, and yeast two hybrid analyses. We will also study their functions by creating gene over-expressed or silenced transgenic petunia plants and analysis the changes in transcriptome and phenotypes, especially the changes in shoot branching pattern and flower shape. These results will help us to understand how duplication and diversification of ECE clade of TCP genes shape petunia plant architecture. At the same time, the snapdragon CYC gene and petunia ECE clade genes will be engineered under the control of the promoters of LjCYC2 or monkey flower CYC2 clade genes respectively and transfer into petunia to see if additional new transcription patterns of ECE clade genes can enhance zygomorphic features of the petunia flower. We hope these transgenic plants can mimic the evolution of zygomorphy from actinomorphy. The results of these studies will also help us to evaluate the strategies of creating novel flowers by genetic engineering using TFs as target genes.

创造新奇的形态特征是观赏植物研究的重要目标，而植物进化形成新形态特征的过程中转录因子基因重复和功能分化扮演重要角色，因此，研究转录因子基因重复和功能分化与观赏性状发育的关系将有助于园艺产业的发展。TCP家族是植物特有的调控细胞增殖和生长的转录因子，其ECE支与株型和两侧对称花型发育相关。矮牵牛是具轻微两侧对称花、株型变异丰富、易于遗传操作的观赏植物，其分枝和花型与已研究过ECE支TCP基因功能的植物存在差异。项目在前期克隆ECE支TCP基因和进行初步的表达模式分析基础上，利用多种反向遗传学研究方法，分析ECE支TCP基因在矮牵牛株型和花型发育中的作用是否有其特殊之处；同时，将在花发育后期背腹不对称表达的外源ECE支基因导入矮牵牛，实现ECE支基因的进一步重复和功能分化，研究能否用基因工程手段模拟植物的花由辐射对称向两侧对称进化的过程，探索转录因子基因重复和启动子操作在创造新奇花卉中的应用。